One or two motors (split from 'Is there a valid reason for a pony bottle')

[MichaelMc]

@MaxBottomtime, I saw your boat has two outboards. That might be for a swim ladder between them, but having two is handy in case one breaks in a hostile ocean environment. Did the redundancy play any role in going with two?

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A ScubaBoard Staff Message...

This post, and the following, have been split from the Basic Scuba thread Is there a valid reason for a pony bottle

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[MaxBottomtime]

@MaxBottomtime, I saw your boat has two outboards. That might be for a swim ladder between them, but having two is handy in case one breaks in a hostile ocean environment. Did the redundancy play any role in going with two?

It weighs 5400 pounds empty. Add 150 gallons of fuel, 30 gallons of fresh water, three divers with six steel tanks and the weight of two outboards and it needs all that horsepower to push it. I can run on one motor but only less than 10mph, and it sucks fuel when I do that.

 

[MichaelMc]

and it need all that horsepower to push it. I can run on one motor but only less than 10mph, and it sucks fuel when I do that.

I meant why two 150s instead of one 300. I know many believe in a philosophy of one is none, two is one.

 

[flyboy08]

I meant why two 150s instead of one 300. I know many believe in a philosophy of one is none, two is one.

Like an airplane..two beats one!

 

[MaxBottomtime]

I meant why two 150s instead of one 300. I know many believe in a philosophy of one is none, two is one.

That's the way the boat is made. We chose the C-Dory Tomcat for many reasons. The large pilot house allows us to be out of the elements. The catamaran hull offers greater stability than monohulls, which is great when you're trying to get into and out of scuba gear. It has a marine head rather than a port-o-potty (Merry's insistence). It comes with a stove/heater, refrigerator/freezer, queen size V-berth, live well and two fish lockers, which we use for storage and a freshwater shower. I added a twenty foot hose so we can shower and rinse gear anywhere on deck. I added a VHF radio, GPS/RADAR/Fishfinder and four hundred feet of anchor chain. It's set up as a perfect dive boat for us. I don't need anything bigger.

 

[Colliam7]

Like an airplane..two beats one!

We-e-e-l-l-l, there are probably (at least) two schools of thought on that. Nonetheless, I get the point.

Gareth makes a good point about independent doubles, vs manifolded doubles.

But, I readily agree - in the case of two 150 hp motors vs one 300 hp unit, your point is spot on!

 

[MichaelMc]

That's the way the boat is made. We chose the C-Dory Tomcat for many reasons. The large pilot house allows us to be out of the elements. The catamaran hull offers greater stability than monohulls, which is great when you're trying to get into and out of scuba gear. It has a marine head rather than a port-o-potty (Merry's insistence). It comes with a stove/heater, refrigerator/freezer, queen size V-berth, live well and two fish lockers, which we use for storage and a freshwater shower. I added a twenty foot hose so we can shower and rinse gear anywhere on deck. I added a VHF radio, GPS/RADAR/Fishfinder and four hundred feet of anchor chain. It's set up as a perfect dive boat for us. I don't need anything bigger.

I wasn't at all questioning the size of the boat or its suitability for your diving. I was more working toward a comment that it has some built in redundancy in its use of two completely separate engines. Something at odds with your apparent lack of approval of individual redundancy in diver air supply. It seems the engines may not have been a choice on your part, unless you picked that model because of its redundancy. But the contrast is odd. You have a boat with two engines, yet feel against redundant air.

Understanding that your friend has some training issues.

 

[MaxBottomtime]

They are not redundant motors. It takes that much power to push the boat. With a catamaran hull, you get better speed and mileage by having one motor push each pontoon. It's not an extra motor for "just in case". Some boats with a single outboard or inboard motor can have a kicker, a small outboard used for trolling. They can be used in a pinch but again, they don't push the boat very fast.

 

[flyboy08]

They are not redundant motors. It takes that much power to push the boat. With a catamaran hull, you get better speed and mileage by having one motor push each pontoon. It's not an extra motor for "just in case". Some boats with a single outboard or inboard motor can have a kicker, a small outboard used for trolling. They can be used in a pinch but again, they don't push the boat very fast.

Its redundant! If you run out of gas on one, your out on both...but if you drop a screw on one, you still have one to get you back home.

 

[MichaelMc]

They are not redundant motors. It takes that much power to push the boat. With a catamaran hull, you get better speed and mileage by having one motor push each pontoon. It's not an extra motor for "just in case". Some boats with a single outboard or inboard motor can have a kicker, a small outboard used for trolling. They can be used in a pinch but again, they don't push the boat very fast.

I fully get that you need 300hp, and that all of it on one side would not be very good. But 300 in the center might work really well. So why did they build it with two motors? Maybe because if one breaks, you at least still have half your horsepower, if now off center.

It is redundancy, just at a reduced performance level. It would likely keep you pointed into swells as opposed to turning sideways to heavy seas. Or off a reef, or home slowly.